
public class zy12 {
   public static double fun(double x){
	   
	return 4-x*x;
  }
  public static void main(String[] args){
	  int i,num=100000000,n=0;
	  double x,y;
	  for(i=0;i<=num-1;i++){
		  x=Math.random()*4-2;
		  y=Math.random()*4;
		  if(y<=fun(x))
			  n++;
	  }
	  System.out.printf("%f\n",16.0*n/num);
  }
}
